Safe Haskell	Safe-Inferred
Language	GHC2021

Job

Contents

Queue
Work
Meta
Id
Nice

Synopsis

data Queue job = Queue {
- push :: Nice -> UTCTime -> job -> IO Id
- pull :: Acquire (Maybe (Work job))
- prune :: forall a. Monoid a => (Id -> Meta -> job -> (Bool, a)) -> IO a
}
push :: forall job m. MonadIO m => Queue job -> Nice -> UTCTime -> job -> m Id
prune :: forall job a m. (Monoid a, MonadIO m) => Queue job -> (Id -> Meta -> job -> (Bool, a)) -> m a
data Work job = Work {
- id :: Id
- job :: job
- meta :: Meta
- retry :: Nice -> UTCTime -> IO ()
- finish :: IO ()
}
retry :: forall job m. MonadIO m => Work job -> Nice -> UTCTime -> m ()
finish :: forall job m. MonadIO m => Work job -> m ()
data Meta = Meta {
- alive :: Maybe UTCTime
- nice :: Nice
- wait :: UTCTime
- try :: Word32
}
data Id
unsafeIdFromUUID7 :: HasCallStack => UUID -> Id
idFromUUID7 :: UUID -> Maybe Id
newId :: MonadIO m => m Id
newtype Nice = Nice {
- int32 :: Int32
}
nice0 :: Nice

Queue

data Queue job Source #

A job Queue.

jobs can be pushed to the Queue for eventual execution, pulled from the Queue for immediate execution, and the Queue itself can be pruned.
Job.Memory.queue is an in-memory implementation that can serve as reference.
Other backends are expected to provide a Queue implementation.

Constructors

Queue

Fields

push :: Nice -> UTCTime -> job -> IO Id
Push new job to the queue so to be executed after the specified UTCTime, which may be in the past. Throws if the Queue has already been released.
pull :: Acquire (Maybe (Work job))
Pull some Work from the queue
- If the Queue itself has been released, then returns Nothing right away.
- Otherwise, blocks until Work is available.
- On ReleaseExceptionWith, the job is automatically rescheduled for re-execution after a few seconds. This behavior can be overriden by using Work's retry or finish.
- On ReleaseNormal or ReleaseEarly, the job is automatically removed from the Queue. This behavior can be overriden by using Work's retry or finish.
prune :: forall a. Monoid a => (Id -> Meta -> job -> (Bool, a)) -> IO a
Prune jobs from the Queue, keeping only those for which the given function returns True (like filter). Allows collecting some additional Monoidal output. The given jobs are in no particular order. Throws if the Queue has already been released. IMPORTANT: If you remove a job that is currently active, it might be pushed back to the Queue later if required by retry or a Work exception.

push :: forall job m. MonadIO m => Queue job -> Nice -> UTCTime -> job -> m Id Source #

Like the push field in Queue, except with a bit more polymorphic type and intended to be used as a top-level function.

prune :: forall job a m. (Monoid a, MonadIO m) => Queue job -> (Id -> Meta -> job -> (Bool, a)) -> m a Source #

Like the prune field in Queue, except with a bit more polymorphic type and intended to be used as a top-level function.

Work

data Work job Source #

A job together with its Queue execution context details.

As soon as you get your hands on a Work, which you do through pull, start working on it right away.

Constructors

Work

Fields

id :: Id
Unique identifier for the scheduled job (and re-scheduled job, see pull and retry).
job :: job
The actual job to be carried out.
meta :: Meta
Metadata accompanying the job being performed.
retry :: Nice -> UTCTime -> IO ()
Once this Work is released, reschedule to be executed at the specified UTCTime at the earliest.
See the documentation for Queue's pull.
```
retry _ _ >> retry n t  ==  retry n t
finish    >> retry n t  ==  retry n t
retry n t >> finish     ==  finish
```

finish :: IO ()

Once this Work is released, remove it from the execution queue.

See the documentation for Queue's pull.

finish    >> retry n t  ==  retry n t
retry n t >> finish     ==  finish
finish    >> finish     ==  finish

Instances

Instances details

Functor Work Source #
Instance details Defined in Job Methods fmap :: (a -> b) -> Work a -> Work b # (<$) :: a -> Work b -> Work a #

retry :: forall job m. MonadIO m => Work job -> Nice -> UTCTime -> m () Source #

Like the retry field in Work, except with a bit more polymorphic type and intended to be used as a top-level function.

finish :: forall job m. MonadIO m => Work job -> m () Source #

Like the finish field in Work, except with a bit more polymorphic type and intended to be used as a top-level function.

Instances

Instances details

Show Id Source #
Instance details Defined in Job Methods showsPrec :: Int -> Id -> ShowS # show :: Id -> String # showList :: [Id] -> ShowS #
Eq Id Source #
Instance details Defined in Job Methods (==) :: Id -> Id -> Bool # (/=) :: Id -> Id -> Bool #
Ord Id Source #
Instance details Defined in Job Methods compare :: Id -> Id -> Ordering # (<) :: Id -> Id -> Bool # (<=) :: Id -> Id -> Bool # (>) :: Id -> Id -> Bool # (>=) :: Id -> Id -> Bool # max :: Id -> Id -> Id # min :: Id -> Id -> Id #
Hashable Id Source #
Instance details Defined in Job Methods hashWithSalt :: Int -> Id -> Int # hash :: Id -> Int #
HasField "uuid7" Id UUID Source #
Instance details Defined in Job Methods getField :: Id -> UUID #

unsafeIdFromUUID7 :: HasCallStack => UUID -> Id Source #

idFromUUID7 :: UUID -> Maybe Id Source #

newId :: MonadIO m => m Id Source #

Nice

newtype Nice Source #

Nice value for a job.

The lower the value, the less “nice” a job is to other jobs. Meaning it will have priority over other jobs, and possibly be allocated more resources.
The higher the value, the “nicer” a job is to other jobs. Meaning it will have less priority over other jobs, and possibly allow competing jobs to take more resources.
Use nice0 (i.e,. Nice 0) as default Nice value.

Constructors

Nice
Fields int32 :: Int32

Instances

Instances details

Bounded Nice Source #
Instance details Defined in Job Methods minBound :: Nice # maxBound :: Nice #
Enum Nice Source #
Instance details Defined in Job Methods succ :: Nice -> Nice # pred :: Nice -> Nice # toEnum :: Int -> Nice # fromEnum :: Nice -> Int # enumFrom :: Nice -> [Nice] # enumFromThen :: Nice -> Nice -> [Nice] # enumFromTo :: Nice -> Nice -> [Nice] # enumFromThenTo :: Nice -> Nice -> Nice -> [Nice] #
Show Nice Source #
Instance details Defined in Job Methods showsPrec :: Int -> Nice -> ShowS # show :: Nice -> String # showList :: [Nice] -> ShowS #
Eq Nice Source #
Instance details Defined in Job Methods (==) :: Nice -> Nice -> Bool # (/=) :: Nice -> Nice -> Bool #
Ord Nice Source #
Instance details Defined in Job Methods compare :: Nice -> Nice -> Ordering # (<) :: Nice -> Nice -> Bool # (<=) :: Nice -> Nice -> Bool # (>) :: Nice -> Nice -> Bool # (>=) :: Nice -> Nice -> Bool # max :: Nice -> Nice -> Nice # min :: Nice -> Nice -> Nice #

nice0 :: Nice Source #

nice0 = Nice 0

Show Meta Source #
Instance details Defined in Job Methods showsPrec :: Int -> Meta -> ShowS # show :: Meta -> String # showList :: [Meta] -> ShowS #
Eq Meta Source #
Instance details Defined in Job Methods (==) :: Meta -> Meta -> Bool # (/=) :: Meta -> Meta -> Bool #
Ord Meta Source #	Order compatible with the one in `prune`.
Instance details Defined in Job Methods compare :: Meta -> Meta -> Ordering # (<) :: Meta -> Meta -> Bool # (<=) :: Meta -> Meta -> Bool # (>) :: Meta -> Meta -> Bool # (>=) :: Meta -> Meta -> Bool # max :: Meta -> Meta -> Meta # min :: Meta -> Meta -> Meta #